1. Field of the Invention
This invention relates to a method of testing the auditory responses in human beings.
2. Prior Art
Testing for auditory response in humans is well known, and modern technology has provided sophisticated instruments designed to produce measures of the auditory response (audiograms) in an accurate and reproducible manner. A number of manufacturers in the United States and other countries make such devices for use in clinics, laboratories, and enterprises engaged in the sale of amplification devices such as hearing aids.
Prior art audiometric devices utilize a pure tone, i.e., a signal of a single, selected frequency at a number of predetermined frequency levels to test the response of the subject at each such frequency level through a range of signal intensity. The auditory response of the subject is then presented as the familiar audiogram.
The pure tone or signal at a predetermined frequency offers the advantage of being mechanically or electronically generated with identical reproduction, thus permitting a theoretical uniformity of test results from one testing center to another testing center and from one audiologist to another audiologist, and from one instrument to another instrument.
However, while the use of single-tone testing permits uniformity of tests, the test results are not always uniform or satisfactory. This has proven to be particularly true in the determination of proper amplification aids for individuals with impaired hearing. It has also been observed that there are anomalies in response to pure tones, particularly among infants and very young children with limited grasp of the testing situation. It has been observed, particularly with infants and young children, that use of familiar words and phonemes permits obtaining an audiogram that is different in significant respects from that obtained with pure tone signals. Moreover, the use of familiar words and phonemes provides test results which reflect more accurately the frequencies at which amplification assistance is desired and the extent of such assistance.
Northern and Downs, in Hearing in Children, Williams & Wilkins Co., Baltimore, Md. (1974), present results comparing thresholds for speech and a warbled pure tone and conclude that speech produces a significantly lower threshold than pure tones for tested individuals at varying age levels. Eisenberg, in Auditory Competence in Early Life, the Roots of Communicative Behavior, University Park Press, Baltimore, Md. (1976), cites numerous studies which have shown that speech is the most effective auditory stimulus for obtaining a response in newborns, infants and young children. Condon and Sander present findings on neonate respnse to speech in "Neonate movement is synchronized with adult speech: Interactional participation and language acquisition," Science, 183:99-101, 1974.
Thus, while there is a general recognition that speech is a more effective elicitor of human response than pure tone for infants, young children, and hard-to-test subjects, speech has not been used for auditory testing because of the inability to obtain quantitative information corresponding to an audiogram.